Fix remote mobile control visibility gate

[mkaoudis]

Summary

• patch the current use-plugin-install-flow visibility bundle for remote mobile control
• preserve the upstream accessRequired guard while allowing Linux hosts to expose the connection UI
• add coverage for the current bundle name/pattern and gate shape

Review order

This PR should be reviewed after #322 lands or main otherwise gets the same PR-only Nix rollout handling. The code change is independent, but its current Nix check is red only because upstream Codex.dmg metadata is ahead of the committed flake pins.

Why / user-visible behavior

• The current upstream bundle moved the remote-control visibility gate into use-plugin-install-flow, so the opt-in Linux mobile remote-control feature can miss the connection UI.
• With linux-features/remote-mobile-control enabled, Linux hosts can expose the mobile remote-control connection UI while still respecting upstream accessRequired state.

Scope and limitations

• This stays inside the opt-in linux-features/remote-mobile-control feature and does not enable the feature by default.
• No committed features.example.json, distro packaging, installer, or updater behavior changes are included.
• Unrelated upstream/Nix pin drift is left out of scope for separate maintenance changes.

Source of truth

• linux-features/remote-mobile-control/patch.js
• linux-features/remote-mobile-control/test.js

Test plan

• node --test linux-features/remote-mobile-control/test.js
• node --test scripts/patch-linux-window-ui.test.js
• git diff --check origin/main..HEAD

CI note

• Current CI has Debian/RPM/pacman packaging and Rust/smoke tests passing.
• The remaining Nix Package Builds failure is from validate-nix-pins.sh reporting an upstream DMG app-version pin mismatch: expected 26.519.81530, got 26.519.41501. That happens before this feature patch is exercised and is addressed by fix(ci): tolerate upstream DMG rollout in PR Nix checks #322.

[ilysenko]

Reviewed the updated head after rebasing onto current main. The remote-mobile-control patch stays scoped to the opt-in linux-feature, local tests pass, and the fresh CI run is green.